There are several activities in an ultrasound examination that require a pointing device. These activities, which can include measuring, tracing, navigating, caliper placing, annotating, and menu selection, are typically performed using a trackball as a pointing device. There are, however, several disadvantages associated with using a trackball. First, because a trackball is not environmentally sealed, ultrasound coupling gel can collect within the internal mechanisms of the trackball and cause the trackball to malfunction, resulting in a costly service call. Second, trackballs are expensive and have a relatively high power consumption. Third, trackballs can be a source of repetitive stress injuries since a user is required to lift and reposition his hand to roll the pointer across the entire length of a displayed screen. Trackballs also occupy a large amount of space in the user-interface area on the ultrasound machine. Not only is this a limiting factor in size reduction of the user-interface area, but it is also a source of accidental activation of the pointing device.
There is, therefore, a need for an ultrasound imaging system with an improved pointing device that will overcome these disadvantages.